After an enterprising first half hour by both sides Alfie Gaughan gave the Wrens a 35th minute lead, before livewire striker Blessing Adalaye was twice upended in the box, and twice expertly slotted the resulting spot kicks.
With Rainworth comfortably 3-0 up at the break Jack Gibb gave the Stags brief hope three minutes into the restart, but three minutes later Adam Jackson restored the Wrens' three-goal cushion.
That was the sign for multiple substitutions and although there was no further score the changes did not affect the Wrens' dominance for most of the rest of the half.
Asked whether the Stags had underestimated Rainworth in choosing to send their young side, Wrens boss Marvin conceded: "To be fair, we were an unknown to them. We are a brand new team so it was hard for them to judge, but wew knew we would go out there and give them a good game.
"I'm happy at the progress made from last week, we could and maybe should have scored more and need to be a bit more clinical in open play, but we're lookking really good at set pieces, and we were fantastic off the ball. We know that Mansfield would try to pull us apart, and they did at times, but we got to grips with it.
"Their 3-5-2 formation contrasted with the 4-3-3 of Bolsover but the lads handled the problems presented to them really well."
Rainworth have no game on Saturday, but on Tuesday night they will entertain Evo-Stik Premier League Basford United which will present potentially their biggest test of pre-season.
"I think they will bring a mixed side," said Marvin. "They've got two sides and so many players so it's another unknown for us, but I'm happy with unknowns because they give us new problems to solve, and if we can solve every problem presented to us before August we will go into the new season very well prepared."